Most liked posts in thread: 2004 R53 (re)Build Thread

Me too... check this out. Two days ago we got new codes in addition to cyl 2 misfire and cyl 2 misfire with low fuel. Now we get two ignition coils codes, for “A” and “B.”

The first thing I did on this back in January was put in brand new plug wires and ignition coil. Nothing changed and I returned them, stuck with what we had which are only 20,000 miles old. But. Second guessing now. What if I didn’t properly clear the codes and thought the code was still present but really I didn’t do the process right? At some point in this work I realized that I had to clear the codes a certain way to get them go away so the computer could start logging the criteria correctly again to show codes again or not. I think it’s possible I didn’t do it right back in January when I put in new wires and coil.

I have new plug wires arriving today, will pop this in tonight and properly clear codes and see what it does this weekend. If it’s still misfiring then I’ll get into injector swaps.

There is just not much else left to do. This is coming down to something very simple that I’ve been blind to so far.


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Frustration level is high!

Plug wires did nothing (forgot to come back for that update / non-update). But they’re good NGK wires so I left them in. And they’re blue, so extra 20 hp even on three cylinders right?!

I still need to try the injector swap. Just no time to get into that. Hoping to do it by Sunday this weekend. After that, if the misfire doesn’t move with injector 2, I think I’ll be officially out of ideas.

The misfire is pretty bad now, constant at idle and if it idles long enough I’m pretty sure cylinder 2 is shutting down all the way. As long as it doesn’t idle for very long, it still feels great under power.


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makes sense to test the injector again to be sure it's repeating this behavior and that I didn't just see it go off because the tester shook itself loose. we did check it twice with the same result, but I didn't think to make sure the tester was seated after the engine started up.

 

I didn’t know about that option with DT, that’s a great idea.

You’re right, could be the wired connector that plug into the injector. I’ve ruled out several things but now it could be anything from the injector plug on back to the ECU. I also don’t think it’s the wiring harness though now that I’ve had more time to read responses and think. I don’t think a wiring problem would let the injector start up with the other three as normal and then shut down.

There is a thread on another forum where a guy was chasing a misfire on cylinder 2 like me. He discovered this behavior too where injector 2 worked but shut off after a few seconds of the engine idling. In his case, he tested the resistance of his spark plugs and found the plug on cylinder 2 to have really high resistance. He replaced it and the problem was solved. That’s not going to be the solution for me. Since the misfire started, I swapped plugs with no change, then put in a brand new plug with no change, then took the cylinder head out for the valve job, then I put in all four brand new plugs after the cylinder head went back in. I haven’t swapped them around again just yet but as 00Mini said that’s easy, and I can try that, but I can’t see anything different happening there.

On the spark plug thought, maybe this... when I tested plug 2 for spark, I didn’t want to crank the engine much at all to do that and I didn’t want to turn it over all the way. I pulled all four plug wires so that the engine would crank, show me the spark and that was it. We cranked it only two or three cranks, just enough that I saw the spark and said okay. But now I wonder if that plug is what stops firing after a few seconds of idling. Still it wouldn’t be solved with a new spark plug and I have new plug wires in for the second time, so I’d have to test the signal from the ignition coil. At least to rule that out and then be back to the ECU or injector wiring or injector wire plug theory.

I’m done to a chicken and egg thing. Either the cylinder starts to misfire first and then the ECU shuts off the injector (does it even work that way?) or something tells the ECU to shut off the injector which then causes an obvious misfire (logging the misfire code).


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Yeah I’ll definitely try chatting with Chad, happy to send some dollars his way for the effort too.

Question about the spark plug test. I didn’t crank the engine very long because the whole situation was making me nervous. I unplugged all four plugs so that it wouldn’t turn over, but if I keep the other three plugged in so the engine will run, is that okay? Am I flooding the cylinder with fuel when it’s cranked with the cylinder 2 plug out and not there to ignite the fuel? Or could I avoid that by unplugging that injector? It all seems kinda hairy but I’ve never done it before so it’s always an adventure with each of the new things I learn to do to this car.


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I should be able to share the videos from the tech... you can see all the other mess this car has going on before he even gets to the engine trouble. Kinda feeling like a nightmare.

video 1 - this ends right as he gets to the camshaft
https://api.mykaarma.com/video-walkaround/details?inspection_uuid=6089870263ef0b000135db8f&fileType=image_and_video

video 2 - picks up where first video left off
https://api.mykaarma.com/video-walkaround/details?inspection_uuid=608987891c93b3000111d91c&fileType=image_and_video

 

I can no longer tell if you guys are the angel or the devil on my shoulders!

I’ll be diving into research and a lot of thinking this weekend. I’ll be posting more as I think this through.